1. Field of the Invention
The present invention relates to a syringe and a syringe assembly having such an arrangement that a medical fluid held in a barrel is expelled from the barrel via a fluid expelling passage of the barrel, as well as an apparatus for manufacturing the same.
2. Discussion of the Background
Generally, a syringe assembly includes:
a tubular barrel having an open proximal end through which a medical fluid is introduced into the barrel, and a distal end with a fluid expelling passage through which the medical fluid held in the barrel is expelled into the body of a person to be treated; PA1 an elastic seal disposed within a barrel chamber in fluid-tight and axially-sliding engagement with the inner wall of the chamber; and PA1 a plunger rod having a proximal end projecting proximally from the proximal end of the barrel, and a distal end interconnected to the seal, so that the medical fluid held in the barrel chamber is expelled from the barrel chamber via the fluid expelling passage by sliding the seal by using the plunger rod.
In the above arrangement, it is necessary to slide the seal within the barrel chamber as maintaining the seal in fluid-tight engagement with the inner wall of the barrel chamber. To achieve high slidability of the seal relative to the inner wall of the barrel chamber, a conventional syringe assembly employs lubricant such as a silicon oil, which is applied to the entire surface of the inner wall of the barrel chamber so as to form a silicon film.
Although the silicon oil is not harmful even if it is introduced into the body, it is preferable to limit the quantity of the silicone oil introduced into the body. However, the conventional syringe of the above arrangement causes the medical fluid filled in the barrel chamber to constantly contact the silicon film, resulting in a high possibility of elusion of silicon into the medical fluid. Particularly, a pre-filled syringe assembly, which is shipped with the medical fluid therein, causes the medical fluid to contact the silicon film for a prolonged period of time, resulting in increasing the possibility of the elusion of silicon. Further, unlike a barrel formed from glass, a barrel formed from plastic may increase the possibility of the elusion of the silicon into the medical fluid, since silicone cannot be baked on the plastic barrel.
Therefore, the present invention has been conceived to solve the above problems in a syringe of the type that includes the tubular barrel, the seal held within the barrel chamber in fluid-tight and axially sliding engagement with the inner wall of the barrel chamber of the barrel, so that a fluid held in the chamber is expelled from the barrel chamber by sliding the seal. It is an object of the present invention to provide a syringe and a syringe assembly capable of preventing lubricant from being introduced into a fluid or a fluid forming drug held in the barrel chamber, as maintaining the seal in fluid-tight and sliding engagement with the inner wall of the barrel chamber.
It is another object of the invention to provide an apparatus for manufacturing the syringe and the syringe assembly of the above arrangement.